Thermoplastic resin composition containing amorphous polyimide

ABSTRACT

A thermoplastic resin composition comprising an aromatic polyester and an amorphous polyimide. There is provided, for example, a polyalkylene naphthalate resin composition having greatly improved moldability and enhanced crystallinity, and being free from troubles such as bleeding out after molded. The resin composition further exhibits reduced emission of fluorescence and excellent weatherability and delamination resistance.

TECHNICAL FIELD

This invention relates to a thermoplastic resin composition comprisingan aromatic polyester and an amorphous polyimide. More specifically, itrelates to a thermoplastic resin composition comprising an aromaticpolyester and an amorphous polyimide and having excellent moldability.

BACKGROUND TECHNOLOGY

Polyethylene terephthalate is used as a raw material for containers forjuice, refreshing drink, carbonate drink, seasoning, detergent, cosmeticand the like, since it is excellent in mechanical strength, heatresistance, transparency and gas-barrier properties, as compared withother plastic materials. In some applications, however, it has suchproblems that it cannot be filled or fully sterilized at hightemperatures due to the lack of sufficient resistance to high heat, thatit shows low efficiency because of its low alkali washing temperaturefor recycling use, and that the amount of the content decreases due toits insufficient gas-barrier properties. Therefore, the development ofpolyethylene terephthalate having excellent heat resistance and highgas-barrier properties has been strongly desired.

Polyethylene-2,6-naphthalene dicarboxylate (to be abbreviated as PENhereinafter) is widely used as a raw material for magnetic films, drinkbottles, packing materials and a variety of moldings. However, since aconventional resin containing a naphthalene ring such as PEN has a lowcrystallization speed, it is desired to improve crystallization speedfor the acceleration of its molding cycle and to rise crystallinity forthe improvement of its dimensional stability, chemical resistance andheat resistance. As solutions for these problems, there have beenproposed many methods including one which uses a high-temperature moldand one in which a crystal nucleating agent or crystallization promotingagent is added.

Japanese Laid-Open Patent Application 51-143060 discloses a polyetherimide/polyester mixture containing a polyether imide represented by thefollowing formula (A): ##STR1## wherein a is a number larger than 1, Zis an o-phenylene group, p-phenylene group or aromatic group having upto 17 carbon atoms, and R is a divalent organic group such as anaromatic hydrocarbon having 6 to 20 carbon atoms,

and a polyester represented by the following formula (B): ##STR2##wherein b is a number larger than 1, R' is an alkylene group having 1 to10 carbon atoms, and two carbonyl groups are at the meta- orpara-position.

This mixture exhibits a lower melt viscosity than that of the polyetherimide.

Japanese Laid-Open Patent Application 59-37161 discloses a heatresistant polyester container made of an unoriented amorphous sheetformed from a resin composition comprising 60 to 99 wt % of apolyethylene terephthalate and 40 to 1 wt % of a polyether imide. Thispublication discloses the same polyether imide as that represented bythe above formula (A) disclosed by the above Japanese Laid-Open PatentApplication 51-143060.

Japanese Laid-Open Patent Application 6-49206 discloses a polyimidecomprising 3,3',4,4'-benzophenone tetracarboxylic dianhydride as amonomer unit and 1,4-diaminobutane as a monomer unit and a polymer blendof the polyimide and a thermoplastic polymer including polyethyleneterephthalate or polybutylene terephthalate. Example III shows that themelting point of a polyimide obtained from 3,3',4,4'-benzophenonetetracarboxylic anhydride and diamine consisting of 75% of1,4-diaminobutane and 25% of 3,3-oxydianiline could not be detected,while polyimides in other examples are crystalline polyimides having amelting point.

On pages 677 and 678 of Research Disclosure November 1987 and pages 1453to 1458 of ANTEC' 95 is disclosed a blend of a polyether imide(ULTEM1000 of GE Corp.) comprising recurring units represented by thefollowing formula and polyethylene-2,6-naphthalene dicarboxylate (PEN).##STR3##

Although the glass transition temperature of this blend is improved dueto the high glass transition temperature of the ULTEM1000, it isdifficult to mold the blend due to its increased melt viscosity. Inaddition, the obtained molded article is fragile, and its delaminationwhich occurs when a film is bent to undergo stress is not improved.

Japanese Laid-Open Patent Application 7-228761 discloses a polyesterresin composition comprising a copolyester consisting of ethyleneterephthalate units and ethylene naphthalate units and the polyetherimide substantially same as that represented by the above formula (A).The publication also discloses that this resin composition is used inexterior trim parts such as auto parts, or in housings for officeequipment, or the like.

U.S. Pat. No. 5,057,595 discloses a composition comprising a copolyestercomprising 4,4'-biphenyldicarboxylic acid as an acid component and1,4-cyclohexane dimethanol and ethylene glycol as glycol components anda modifier such as a composition containing ULTEM of GE Corp.

U.S. Pat. No. 5,037,946 discloses a composition comprising a copolyestercomprising 4,4'-biphenyldicarboxylic acid as an acid component and1,6-hexanediol and ethylene glycol as glycol components and the samemodifier as described above.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a thermoplasticresin composition containing an amorphous polyimide.

It is another object of the present invention to provide a thermoplasticresin composition which contains an amorphous polyimide and hasexcellent moldability.

It is still another object of the present invention to provide athermoplastic resin composition which contains an amorphous polyimide,is excellent in transparency and delamination resistance, and comprisespolyethylene-2,6-naphthalene dicarboxylate or the like as athermoplastic resin.

It is still another object of the present invention to provide athermoplastic resin which contains an amorphous polyimide, exhibitsexcellent heat resistance, and comprises polyethylene terephthalate orthe like as a thermoplastic resin.

Other objects and advantages of the present invention will becomeapparent from the following description.

According to the present invention, the above objects and advantages ofthe present invention can be attained by a thermoplastic resincomposition which comprises an aromatic polyester containing an aromaticdicarboxylic acid as a main acid component and an aliphatic glycolhaving 2 to 8 carbon atoms as a main diol component and an amorphouspolyimide comprising recurring units represented by the followingformula (1): ##STR4## wherein Ar is an aromatic group having 6 to 15carbon atoms and R is an aliphatic group having 6 to 30 carbon atoms oralicyclic group having 4 to 30 carbon atoms,

and which contains 5 to 99.95 wt % of the aromatic polyester and 0.05 to95 wt % of the amorphous polyimide, based on the total weight of thearomatic polyester and the amorphous polyimide.

The aromatic polyester used in the present invention contains anaromatic dicarboxylic acid as a main acid component and an aliphaticglycol having 2 to 8 carbon atoms as a main diol component.

The aromatic dicarboxylic acid in the present invention is preferablycontained in an amount of 80 to 100 mol %, more preferably 90 to 100 mol%, particularly preferably 95 to 100 mol %, based on the acid componentsof the aromatic polyester. The aliphatic glycol having 2 to 8 carbonatoms is preferably contained in an amount of 80 to 100 mol %, morepreferably 90 to 100 mol %, particularly preferably 95 to 100 mol %,based on the diol components of the aromatic polyester.

Preferred examples of the aromatic dicarboxylic acid includeterephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid,diphenyldicarboxylic acid, diphenoxyethane dicarboxylic acid,diphenylether dicarboxylic acid, diphenylsulfone dicarboxylic acid orthe like. These aromatic dicarboxylic acids may be used alone or incombination of two or more.

Illustrative examples of other acid components which may be used incombination with the aromatic dicarboxylic acid in an amount of 20 mol %or less include alicyclic dicarboxylic acids such ashexahydroterephthalic acid and hexahydroisophthalic acid; aliphaticdicarboxylic acids such as adipic acid, sebacic acid and azelaic acid;and oxyacids such as p-β-hydroxyethoxybenzoic acid and ε-oxycaproicacid.

The aromatic dicarboxylic acid is preferably terephthalic acid or2,6-naphthalenedicarboxylic acid.

The aliphatic glycol having 2 to 8 carbon atoms may be eitherstraight-chain or branched. Illustrative examples of the aliphaticglycol include ethylene glycol, trimethylene glycol, tetramethyleneglycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol,diethylene glycol, 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanoland the like. These aliphatic glycols may be used alone or incombination of two or more.

Illustrative examples of other diol components which may be used incombination with the aliphatic glycol having 2 to 8 carbon atom in anamount of 20 mol % or less include 2,2-bis(4'-β-hydroxyphenyl)propane,bis(4'-β-hydroxyethoxyphenyl)sulfonic acid or the like.

The aliphatic glycol having 2 to 8 carbon atoms is particularlypreferably ethylene glycol.

Illustrative examples of the aromatic polyester include polyethyleneterephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polybutylene-2,6-naphthalene dicarboxylate and copolymersthereof. Of these, polyethylene-2,6-naphthalene dicarboxylate ispreferred.

The aromatic polyester preferably has an intrinsic viscosity (dl/g),measured at 35° C. in a phenol/tetrachloroethane mixture solvent (weightratio 60/40), of 0.3 or more. When the intrinsic viscosity is less than0.3, the strength of the molded article obtained from the aromaticpolyester is apt to be insufficient undesirably. The intrinsic viscosityis more preferably 0.4 or more, particularly preferably 0.5 or more.Although there is particularly no upper limit of intrinsic viscosity, anintrinsic viscosity of ca. 5 suffices for practical use.

The amorphous polyimide which is the other component used in the presentinvention comprises recurring units represented by the above formula(1). The term "amorphous" means that a distinctive melting peak cannotbe detected when measured with a differential scanning calorimeter(DSC). Such polyimide is generally a transparent resin.

In the above formula (1), Ar is an aromatic group having 6 to 15 carbonatoms, and R is an aliphatic group having 6 to 30 carbon atoms or analicyclic group having 4 to 30 carbon atoms.

Illustrative examples of the aromatic group represented by Ar include:##STR5## They may be present in the polymer chain alone or incombination of two or more.

Of these, Ar is particularly preferably ##STR6##

The aliphatic group having 6 to 30 carbon atoms, represented by R, ispreferably an aliphatic group having 6 to 12 carbon atoms, and thealicyclic group having 4 to 30 carbon atoms is preferably an alicyclicgroup having 6 to 12 carbon atoms.

Preferred examples of the group R include .paren open-st.CH₂ .parenclose-st._(m) (wherein m is 6 to 12), 2,2,4-trimethylhexamethylene,2,4,4-trimethylhexamethylene and ##STR7## They may be present in thepolymer chain alone or in combination of two or more.

The R in the formula (1) may contain an aliphatic group having 5 or lesscarbon atoms in an amount of less than 50 mol %, preferably 30 mol % orless, more preferably 20 mol % or less, based on the total of R in theformula 1.

Further, the amorphous properties of the polyimide are enhanced and itscompatibility with the aromatic polyester is improved advantageously,when a straight-chain aliphatic group having no side chain (such as amethyl group or the like), such as 1,12-dodecanediamine or the like, isused as the aliphatic group having 6 to 30 carbon atoms, represented byR, in combination of an aliphatic group other than straight-chainaliphatic groups (such as an aliphatic group having a side chain, e.g.,a methyl group) or an alicyclic group having 4 to 30 carbon atoms.

Illustrative examples of the recurring unit represented by the aboveformula (1) preferably include ##STR8## wherein one of R' and R" is ahydrogen atom and the other is a methyl group.

They may be present in the polymer chain alone or in combination of twoor more. A combination consists essentially of the above fourthrecurring unit, that is, a recurring unit represented by the followingformula: ##STR9## wherein R' and R" are the same as defined in the aboveformula, and a recurring unit represented by the following formula:##STR10## is also preferred.

The above amorphous polyimide can be produced by known methods per se.The methods include, for example, (1) one in which a polyamide acid isfirst obtained from starting materials tetracarboxylic dianhydridecapable of deriving the above Ar and diamine capable of deriving theabove R, and its ring is closed either by heating or chemically using achemical dehydrating agent such as a combination of acetic anhydride andpyridine, carbodiimide or triphenyl phosphite; (2) one in whichpolymerization is carried out by heating the above tetracarboxylicdianhydride and diisocyanate capable of deriving the above R to causedecarbonation; (3) one in which tetracarboxylic dianhydride is, as anintermediate step, partially or wholly esterified with a lower alcoholsuch as methanol or ethanol, converted into acid chloride with thionylchloride, chlorine or phosphor pentachloride, allowed to react with thediamine, and subjected to a cyclization reaction; and the like.

Illustrative examples of the tetracarboxylic dianhydride used in theabove methods include pyromellitic dianhydride,benzophenone-3,3',4,4'-tetracarboxylic dianhydride,biphenyl-3,3',4,4'-tetracarboxylic dianhydride,biphenylether-3,3',4,4'-tetracarboxylic dianhydride anddiphenylsulfone-3,3',4,4'-tetracarboxylic dianhydride.

Illustrative examples of the diamine include isophorone diamine,cyclohexanediamine, 1,8-diamino-p-menthane, 2,2,4- or 2,4,4-trimethylhexamethylenediamine, hexamethylenediamine, octamethylenediamine,nonamethylenediamine, decamethylenediamine, undecamethylenediamine,dodecamethylenediamine and the like.

The molecular weight of the amorphous polyimide in the present inventionis not particularly limited. When the amount of the amorphous polyimideadded is small, an amorphous polyimide having a low molecular weight maybe used as far as it does not impair the mechanical properties of theobtained molded article, whereas when its amount is large, use of apolyimide having a high molecular weight is preferred to such an extentthat it does not impair moldability. In general, when the amorphouspolyimide dissolves in a phenol/tetrachloroethane mixture solvent(weight ratio 60/40), it preferably has an intrinsic viscosity measuredat 35° C. of 0.10 or more, more preferably 0.15 or more, particularlypreferably 0.25 or more. Although there is no upper limit of intrinsicviscosity, an intrinsic viscosity of ca. 5 suffices for practical use.

The thermoplastic resin composition of the present invention comprises 5to 99.95 wt %, preferably 40 to 95 wt %, of an aromatic polyester and0.05 to 95 wt %, preferably 5 to 60 wt %, of an amorphous polyimide,based on the total weight of the aromatic polyester and the amorphouspolyimide. More preferably, the aromatic polyester is contained in anamount of 50 to 90 wt % and the amorphous polyimide in an amount of 10to 50 wt %, based on the total weight of the aromatic polyester and theamorphous polyimide.

Further, when the aromatic polyester is a polyester comprising2,6-naphthalenedicarboxylic acid as a main acid component and ethyleneglycol as a main diol component, the aromatic polyester can be containedin an amount of 80 to 99.95 wt % and the amorphous polyimide in anamount of 0.05 to 20 wt %, based on the total weight of the aromaticpolyester and the amorphous polyimide. The resin composition containingsuch a small amount of the amorphous polyimide can suppress thefluorescent color inherent in the aromatic polyester.

In the amorphous polyamide used in the present invention, it ispreferable for the improvement of moldability and crystallinity that adifference between Tg of the polyimide and Tg of the aromatic polyesteris large. When polyethylene-2,6-naphthalene dicarboxylate is used as thearomatic polyester, the difference is preferably 100° C. or lower, morepreferably 40° C. or lower for the improvement of delaminationresistance.

Since the amorphous polyimide used in the present invention generallyhas excellent compatibility with an aromatic polyester, thethermoplastic resin composition of the present invention can exhibit asingle peak derived from glass transition temperature measured at atemperature elevation rate of 20° C./min by DSC.

To produce the resin composition of the present invention, a method inwhich an aromatic polyester and an amorphous polyimide are mixedtogether using a twin-screw extruder is preferably employed. The mixingtemperature must be a temperature at which the decomposition of apolymer does not take place and which is higher than the melting pointof the aromatic polyester. Mixing is substantially impossible to conductat a temperature lower than the melting point of the aromatic polyester.Further, the mixing temperature is preferably higher than the glasstransition temperature of the amorphous polyimide. For example, when thearomatic polyester is poly(1,2-ethylene-2,6-naphthalene dicarboxylate),the mixing temperature is preferably 280 to 290° C.

The amorphous polyimide may be directly added to the aromatic polyester.Alternatively, it may be first dissolved in the aromatic polyester in ahigh concentration to prepare a master polymer in advance and thismaster polymer may be diluted with the aromatic polyester. The masterpolymer can be prepared by mixing together the aromatic polyester andthe amorphous polyimide directly, or by dissolving the amorphouspolyimide and the aromatic polyester in a solvent that can dissolve bothand then removing the solvent by distillation. The solvent is preferablya low molecular weight imide compound having either one of the followingstructures: ##STR11## wherein n is an integer of 1 to 6.

The resin composition of the present invention can contain variousadditives as required. The additives include a fiber reinforcement suchas a glass fiber, metal fiber, aramide fiber, ceramic fiber, potassiumtitanate whisker, carbon fiber or asbesto; a filler such as talc,calcium carbonate, mica, clay, titanium oxide, aluminum oxide, glassflake, milled fiber, metal flake or metal powder; a thermal stabilizeror oxidative stabilizer typified by phosphate or phosphate; opticalstabilizer; ultraviolet absorber; lubricant; pigment; flame retardant;flame retardant aid; plasticizer; crystal nucleating agent; and thelike.

The resin composition of the present invention is of great industrialvalue because it can be developed into fibers, films, and moldedarticles such as various packing materials, drink bottles, containers,tubes, films, covers and casings by making use of excellent propertiesof polyalkylene naphthalate and polymide. Particularly, the resincomposition is very promising and of great value in that the resincomposition is developed into a refillable drink bottle which can befully sterilized at high temperatures and filled at high temperaturesfor recycle use by making use of its heat resistance.

EXAMPLES

The following examples are given to further illustrate the presentinvention, while the present invention shall not be limited thereto. Inthe following examples, "parts" means "parts by weight", and theintrinsic viscosity (dl/g) of a polymer is a value measured at 35° C. ina phenol/tetrachloroethane mixture solvent (a weight ratio: 60/40).

Reference Example 1 (synthesis of polyimide (PIPM))

In a nitrogen atmosphere, 131.5 gram of isophorone diisocyanate was fedinto 2,000 ml of N-methyl-2-pyrrolidone, and 129.0 g of pyromelliticdianhydride was added to this solution at room temperature. Then, thetemperature of the resulting solution was gradually elevated to generatecarbon dioxide. Thereafter, the generation of carbon dioxide came to anend after the solution was heated at 180° C. for 5 hours, and heatingwas therefore stopped. This polymer solution was fully washed with waterand the obtained polymer was dried. The polymer had an intrinsicviscosity of 0.50 (dl/g). This polymer will be called PIPM hereinafter.

Reference Example 2 (synthesis of polyimide (PHPM))

104.5 Gram of trimethyl hexamethylenediamine (a mixture of 2,2,4- and2,4,4-isomers) was fed into 2,000 ml of N-methyl-2-pyrrolidone, and theobtained solution was cooled in an ice bath. Thereafter, 144.0 g ofpyromellitic dianhydride was added to this solution, and polymerizationwas carried out in the ice bath for 8 hours. After 148.2 g of aceticanhydride and 114.7 g of pyridine were added to this system, theresulting solution was stirred at 0° C. for 12 hours. This polymersolution was fully washed with water and the obtained polymer was dried.The polymer had an intrinsic viscosity of 0.30. This polymer will becalled PHPM hereinafter.

Comparative Example 1

Poly(1,2-ethylene-2,6-naphthalene dicarboxylate) (to be abbreviated asPEN hereinafter) having an intrinsic viscosity of 0.71 was melt-kneadedat a polymer temperature of 290° C. for an average residence time ofabout 20 minutes, and extruded using a twin-screw extruder having adiameter of 30 mm and two screws rotating in the same direction (PCM30of Ikegai Ironworks Co., Ltd.). The thus obtained polymer was heated toa temperature of (melting point+30)° C. at a rate of 20° C./min by adifferential scanning calorimeter (DSC), and to ensure accuracy, asample was taken out from the polymer, quenched with dry ice and heatedat a rate of 20° C./min again to obtain its glass transitiontemperature.

The results are shown in Table 1.

Examples 1 to 3

A predetermined amount of PIPM was added to 100 parts of PEN having anintrinsic viscosity of 0.71, and the resulting mixture was melt-kneadedat a polymer temperature of 290° C. for an average residence time ofabout 20 minutes using a twin-screw extruder having a diameter of 30 mmand two screws rotating in the same direction (PCM30 of Ikegai IronworksCo., Ltd.) as in Comparative Example 1. The glass transition temperaturewas obtained in the same manner as in Comparative Example 1.

When PIPM was contained in an amount of 10 wt % of the polymercomposition, the glass transition temperature of the polymer compositionwas increased by 10° C. or more in all of Examples 1 to 3. The resultsare shown in Table 1. In Example 3, the melting point could not bedetected (ND).

Comparative Example 2

ULTEM1000 (of General Electric Corp.) was used in place of PIPM, andmelt-kneaded with PEN as in Example 1. Although the glass transitiontemperature of PEN did rise, an increase in the glass transitiontemperature was smaller than when PIPM was used.

                  TABLE 1                                                         ______________________________________                                                                       Thermal                                          Polyalkylene Proportion of properties                                         naphthalate/ addition (Tg, Tm)                                                Polyimide (Weight ratio) <° C.>                                      ______________________________________                                        Comparative                                                                            PEN           100         118, 265                                     Example 1                                                                     Example 1 PEN/PIPM 90/10 129, 264                                             Example 2 PEN/PIPM 80/20 142, 265                                             Example 3 PEN/PIPM 50/50 218, ND                                              Comparative PEN/UMTEM1000 90/10 122, 267                                      Example 2                                                                   ______________________________________                                    

Example 4 and Comparative Example 3

10 Parts of PEN having an intrinsic viscosity of 0.71 was added to 90parts of the above PIPM and the mixture was well kneaded at 310° C. toprepare a polymer. The polymer was extruded from a 0.5 mm-diameternozzle at 310° C. by a flow tester to obtain a thread-like sample(Example 4). However, PIPM could not be extruded and a thread-likesample could not be obtained from a polymer composed of PIPM alone underthe same conditions (Comparative Example 3). That is, the melt viscosityof PIPM was reduced by adding a slight amount of PEN, wherebymoldability was improved.

Reference Example 3

The above PEN was melt-kneaded using the above twin-screw extruderhaving a diameter of 30 mm and two screws rotating in the same direction(PCM30 of Ikegai Ironworks Co., Ltd.) to obtain a 100 μm-thick film. Theluminous intensity (I₀) of fluorescence from the obtained PEN film wasmeasured in an area not dependent on thickness.

The luminous intensity of fluorescence was measured by comparing theamount of light emission in a fluorescence emission area of 400 to 550nm (with bandpass of 10 nm) at an excitation wavelength of 350 nm(bandpass of 10 nm) with those of the following Examples using theF-2000 Hitachi Fluorescent Spectrophotometer of Hitachi, Ltd.

Examples 5 to 9

100 Parts of PEN having an intrinsic viscosity of 0.71 and apredetermined amount of PIPM or PHPM were mixed together, and themixture was melt-kneaded in the same manner as in Comparative Example 3to obtain a 100 μm-thick film, and the reduction rate of thefluorescence intensity of this film was obtained.

The reduction rate of fluorescence intensity was calculated from thefollowing equation when the luminous intensity of the above ReferenceExample 3 was represented by I₀ and the luminous intensity of Examplesby I.

    Reduction rate of fluorescence intensity=(I.sub.0 -I)/I.sub.0 ×100(%)

The results are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                               Material  Amount of                                                                              Reduction rate                                        to be addition of fluorescence                                                added (parts) intensity (%)                                                 ______________________________________                                        Example 5                                                                              PIPM        0.1      18                                                Example 6 PIPM 1 42                                                           Example 7 PIPM 5 73                                                           Example 8 PIPM 20 92                                                          Example 9 PHPM 5 72                                                         ______________________________________                                    

Examples 10 and 11

A predetermined amount of PIPM was added to 100 parts of polyethyleneterephthalate (PET) having an intrinsic viscosity of 0.71. The mixturewas melt-kneaded at a polymer temperature of 290° C. for an averageresidence time of about 20 minutes, and extruded using a twin-screwextruder having a diameter of 30 mm and two screws rotating in the samedirection (PCM30 of Ikegal Ironworks Co., Ltd.). The thus obtainedpolymer was heated to a temperature of (melting point+30)° C. at a rateof 20° C./min by a differential scanning calorimeter (DSC) and a samplewas taken out from the polymer, quenched with dry ice and heated at arate of 20° C./min again to obtain its glass transition temperature. Theglass transition temperature was greatly improved when PIPM was added toPET. The results are shown in Table 3.

Comparative Example 3

PET having an intrinsic viscosity of 1.01 was melt-kneaded at a polymertemperature of 290° C. for an average residence time of about 20 minutesusing a twin-screw extruder having a diameter of 30 mm and two screwsrotating in the same direction (PCM30 of Ikegai Ironworks Co., Ltd.) asin Examples 10 and 11. The glass transition temperature was obtained inthe same manner as in Examples 10 and 11.

Comparative Example 4

ULTEM1000 (of General Electric Corp.) was mlet-kneaded in place of PIPMin the same manner as in Examples 10 an 11. As shown in Table 3, anincrease in glass transition temperature when ULTEM1000 was added wassmaller than when PIPM was added.

                  TABLE 3                                                         ______________________________________                                                                       Thermal                                          Polyethylene  properties                                                      terephthalate/ Proportion of (Tg, Tm)                                         Polyimide addition <° C.>                                            ______________________________________                                        Comparative                                                                            PET           100         72, 258                                      Example 3                                                                     Example 10 PET/PIPM 90/10 88, 255                                             Example 11 PET/PIPM 75/25 100, 251                                            Comparative PET/ULTEM1000 90/10 81, 255                                       Example 4                                                                   ______________________________________                                    

Example 12 and Comparative Example 5

10 Parts of PET having an intrinsic viscosity of 1.01 was added to 90parts of the above PIPM, and the mixture was well kneaded at 330° C. toprepare a polymer. The polymer was extruded from a 0.5 mm-diameternozzle by a flow tester to obtain a thread-like sample (Example 12).However, a polymer, to which PET was not added, composed of PIPM alonecould not be extruded under the same conditions (Comparative Example 5).

Example 13

20 Parts of PIPM was added to 80 parts of PET having an intrinsicviscosity of 1.01, and the mixture was molten as in Example 10, extrudedfrom the nozzle of the above twin-screw extruder, quenched by coolingwater and cut into a chip of about 3 mm in diameter and length by acutter. The obtained chip had a glass transition temperature of 96° C.The chip was dried with hot air at 160° C. for 5 hours andinjection-molded in a mold being cooled with cooling water at 10° C.,using the M-100DM injection molding machine of Meiki Seisakusho Co.,Ltd., of which a cylinder temperature was set at a temperature of 275°C., to obtain a preform. The preform was a bottomed cylinder having anouter diameter of its cylindrical barrel portion of 22 to 24 mm, athickness of 3.5 mm and a total length of 150 mm and a substantiallyamorphous achromatic transparent molded article.

The bottomed preform was stretched in an axial direction in abottle-like mold at 100 to 130° C. and expanded in a transversedirection with an inert gas having a pressure of 10 to 20 kg/cm² to molda bottle having an outer diameter of its barrel portion of 82 mm, atotal height of 280 mm and an inner volume of 1,450 to 1,550 ml.

The thus obtained bottle was filled with hot water at 75° C., left tocool at room temperature, and then, measured for its change in volumebefore and after the filling of hot water. The mouth portion of thebottle was cut out and immersed in hot water heated at 75° C. for 1minute to measure a change in the inner diameter of the mouth portionbefore and after this treatment.

Thereafter, the heat resistance of the produced bottle and the glasstransition temperature of the polymer of the obtained bottle wereobtained. The performance of the obtained bottle is shown in Table 4below. The amount of PIPM added in the table indicates wt % of PIPM inthe whole polymer. The glass transition temperature was improved whenPIPM was contained, as compared with when PET was used alone as in thefollowing Comparative Example 6, and heat resistance was greatlyimproved while volume shrinkage and inner diameter shrinkage factorswere reduced. The performance of the obtained bottle is shown in Table 4below.

Comparative Example 6

PET having an intrinsic viscosity of 1.01 was melt-kneaded in the samemanner as in Example 13 and cut into a chip, which was then molded intoa bottle. The performance of the obtained bottle is shown in Table 4below.

                  TABLE 4                                                         ______________________________________                                                    Amount  Glass     Volume Inner dia-                                 Type of transition shrinkage meter shrink-                                    of poly- addition temperature factor age factor                               imide (wt %) <° C.> (%) (%)                                          ______________________________________                                        Example 13                                                                            PIPM    20      96      0.1 or less                                                                          0.1 or less                              Comparative -- -- 72 2.5 0.8                                                  Example 6                                                                   ______________________________________                                    

Reference Example 3 (synthesis of polyimide (PTDO))

62.524 Grams (0.395 mole) of trimethyl hexamethylenediamine (mixture of2,2,4- and 2,4,4-isomers) and 79.146 g (0.395 mole) of1,12-dodecanediamine were fed to 2,000 ml of N-methyl-2-pyrrolidone in anitrogen atmosphere. Thereafter, the solution was cooled in an ice bath,and 245.07 g (0.790 mole) of oxydiphthalic acid was added thereto.Subsequently, polymerization was carried out in the ice bath for 8hours. Then, 240 g of acetic anhydride and 190 g of pyridine were addedto this system, and the resulting solution was stirred at roomtemperature for 12 hours. This polymer solution was fully washed withwater and the obtained polymer was dried. The polymer had an intrinsicviscosity of 0.54. This polymer will be called PTDO hereinafter. Theglass transition temperature of PTDO, measured by a thermal analysismethod to be described later, was 88° C. The crystallinity and meltingpoint of PTDO were not seen.

Reference Example 4 (preparation of PTDO master polymer)

1. Synthesis of AC6I (solvent)

In a nitrogen atmosphere, 498 g of 1,2-cyclohexanedicarboxylic anhydridewas added to 800 ml of toluene, and 283 g (1.2 moles based on 1 mole of1,2-cyclohexanedicarboxylic anhydride) of n-butylamine was addeddropwise to this solution. After the toluene was refluxed for 6 hours,it was confirmed that a predetermined amount of water flew out. Afterthe toluene and the excess of the n-butylamine were distilled out, theproduct (AC4I) represented by the following formula was purified bydistillation. This product had a boiling point of 300° C. or higher atnormal pressure and 115° C. at a pressure of 0.5 mmHg or less. ##STR12##2. Blend of PTDO and PEN

400 Grams of AC6I were added to 200 g of PTDO in a three-necked flask ina nitrogen atmosphere, and the solution was heated to 290° C. whilestirred by an anchor-shaped stirring blade to dissolve PTDO in AC6I.When 800 g of PEN was added to the resulting solution, PEN alsodissolved in this solution in about 5 minutes and a transparent solutionof a composition was obtained. Thereafter, AC6I was completely removedby gradually reducing the pressure to 0.5 mmHg in about 1 minute toprepare a master polymer containing 20 wt % of PTDO.

Examples 14 to 17

The master polymer of PTDO obtained in the above Reference Example 4 wasground and mixed with a PEN chip having an intrinsic viscosity of 0.73.The resulting mixture was melt-kneaded at a polymer temperature of 290°C. for an average residence time of about 20 minutes, and extruded froma T die using a twin-screw extruder having a diameter of 30 mm and twoscrews rotating in the same direction (PCM30 of Ikegai Ironworks Co.,Ltd.) to obtain a 200 μm-thick unstretched film. After the unstretchedfilm was biaxially stretched simultaneously to 3.5×3.5 times at 140° C.,it was fixed to a metal frame and heat set at 240° C. for 10 minutes.The thus obtained polymer, unstretched film, and stretched-and-heat-setfilm were evaluated in accordance with the following methods.

<Thermal Analysis>

The unstretched film was heated to a temperature of (melting point+30)°C. at a rate of 20° C./min by a differential scanning calorimeter (DSC).To ensure accuracy, a sample was taken out from the film, quenched withdry ice and heated at a rate of 20° C./min again to obtain its glasstransition temperature (Tg), crystallization temperature (Tc) andmelting point (Tm).

<Melt viscosity>

The melt viscosity was measured using a flow tester at a shear rate of1,000 sec⁻¹ at 300° C.

<Measurement of fluorescence>

The luminous intensity of fluorescence was measured by comparing theamount of light in a fluorescence emission area of 400 to 550 nm (withbandpass of 10 nm) at an excitation wavelength of 350 nm (with bandpassof 10 nm) with those of Examples, using an unstretched film and theF-2000 Hitachi Fluorescent Spectrophotometer of Hitachi, Ltd.

The reduction rate of fluorescent intensity was calculated from thefollowing equation when the luminous intensity of Comparative Examplewas represented by I₀ and the luminous intensity of Examples by I.

    Reduction rate of fluorescent intensity=(I.sub.0 -I)/I.sub.0 ×100(%)

<Weatherability>

The obtained unstretched film was exposed to ultraviolet light by axenon weather meter according to JIS L0842 (63° C., in the rain), andthe haze of the film caused by the deterioration of the surface wasmeasured by a haze meter.

<Delamination resistance>

The above-described stretched-and-heat-set film was used as a film forthe measurement of delamination resistance. Two of the film to be foldedin MD (4 cm in MD and 5 cm in TD) and two of the film to be folded in TD(5 cm in MD and 4 cm in TD) were prepared (four films in total) for theabove measurement and placed in a desiccator (humidity of 50%, 25° C.)for 3 days to adjust the humidity of each of the films. The films to befolded in MD were folded in a direction parallel to MD and the films tobe folded in TD were folded in a direction parallel to TD. Each of thefolded films was pressed at a pressure of 10 kgf/cm² for 20 seconds, andfurther folded out and pressed at 4 kgf/cm² for 20 seconds. The width ofa stripe formed in each of the folds at 5 sites spaced at equalintervals was measured (total of 20 sites). The average value of thewidths measured at the 20 sites is taken as the width of delamination.It is defined that the film is more easily delaminated as the width ofdelamination is larger.

It is understood from Table 5 that when a predetermined amount of PTDOis blended as shown in Table 5, the glass transition temperature (Tg) ofthe blend polymer lowers according to the content of PTDO and the blendpolymer is made compatible with PEN. It is further understood that whenthe content of PTDO is increased, the crystallization temperature (Tc)peak becomes large and crystallization is promoted, whereby the peakarea of the melting point (Tm) also becomes large. Further, the meltviscosity reduces according to the content of PTDO, thereby improvingthe moldability.

Comparative Example 7

The glass transition temperature and melt viscosity of PEN having anintrinsic viscosity of 0.73 were measured in the same manner as inExamples.

                                      TABLE 5                                     __________________________________________________________________________    Content of                                                                      PTDO Tg Tc Tm Melt viscosity                                                  (wt %/polymer) (° C.) (° C.)(J/g)* (° C.)(J/g)*                                      (poise)                                         __________________________________________________________________________    Comparative                                                                         0      118                                                                              -- (0)  265 (+3.30)                                                                         3700                                              Example 7                                                                     Example 14 1 117 223.3 (-1.76) 265 (+7.96)  3480                              Example 15 3 116 221.6 (-6.62) 265 (+16.81) 3360                              Example 16 5 116 222.4 (-9.99) 265 (+18.16) 3160                              Example 17 10  115   222.0 (-14.61) 265 (+21.18) 2600                       __________________________________________________________________________     *Parenthesized figures indicate peak area (+ heat absorption, - heat          generation)                                                              

Further, the fluorescence emission of the PEN containing PTDO reduced.It was also found that because the haze after 150 hours of exposure tolight was smaller than that of Comparative Example, opticaldeterioration resistance reduced and weatherability improved. It wasalso found that the stretched-and-heat-set film had improveddelamination resistance with a narrower delamination width. Theseresults are shown in Table 6 below.

                  TABLE 6                                                         ______________________________________                                                Reduction                                                               rate of  Delamination                                                         fluorescence Haze after width                                                 % 150 hours (μm)                                                         ______________________________________                                        Comparative                                                                              0          7.0      50                                               Example 7                                                                     Example 14 10 5.8 45                                                          Example 16 33 4.0 20                                                        ______________________________________                                    

Examples 18 to 20

Polyimide was prepared in the same manner as in Example 14 except thatthe acid component was changed to a component shown in Table 7 below,and its glass transition temperature (Tg) was measured. When thepolyimide was blended with PEN (PEN/polyimide weight ratio=80/20), theybecame compatible with each other completely. When the glass transitiontemperature of the blend polymer was measured in the same manner as inExample 14, Tg of all the blend polymer was lower than that of PEN. Theblend polymer had reduced melt viscosity and fluorescence and improvedcrystallinity, weatherability and delamination resistance.

                  TABLE 7                                                         ______________________________________                                                       Intrinsic                                                                              Tg of     Blend (20%)                                   Acid viscosity polyimide with PEN                                             anhydride (dl/g) (° C.) Tg(° C.)                              ______________________________________                                        Example 18                                                                             PMDA      0.38     105.6   114                                         Example 19 BTDA 0.32 103.5 114                                                Example 20 S-BPDA 0.31  96.5 112                                            ______________________________________                                         PMDA: Pyrometallic dianhydride                                                BTDA: 3,3,4,4benzophenonetetracarboxylic dianhydride                          SBPDA: 3,3,4,4bisphenyltetracarboxylic dianhydride                       

Examples 21 and 22

Polyimide was prepared in the same manner as in Example 14 except thatoxydiphthalic acid was used as an acid component and the amine componentwas changed as shown in Table 8 below, and its glass transitiontemperature (Tg) was measured. When this polyimide was blended with PEN(PEN/polyimide weight ratio=80/20), they became compatible with eachother completely. When the glass transition temperature of the blendpolymer was measured in the same manner as in Example 14, it was lowerthan that of PEN. The blend polymer had reduced melt viscosity andfluorescence and improved crystallinity, weatherability and delaminationresistance.

                  TABLE 8                                                         ______________________________________                                                       Intrinsic                                                                              Tg of     Blend (20%)                                   Acid viscosity polyimide with PEN                                             anhydride (dl/g) (° C.) Tg (° C.)                             ______________________________________                                        Example 21                                                                             TMHMDA    0.38     105.2   114.3                                       Example 22 TMHMDA/ 0.48 108.7 115.6                                            HMDA                                                                          (1/1)                                                                      ______________________________________                                         TMHMDA: 2,2,4 and 2,4,4trimethyl hexamethylenediamine                         HMDA: 1,6hexamethylenediamine                                            

Comparative Examples 8 and 9

PEN was mixed with a chip of the ULTEM1000 amorphous polyimide (ofGeneral Electric Corp, Tg of 220° C.) which had a higher glasstransition temperature than that of PEN. The mixture was melt-kneaded bya twin-screw extruder in the same manner as in Examples. The obtainedpolymer was measured for its thermal analysis, melt viscosity anddelamination resistance. It was found that when the amount of theULTEM1000 blend increased, crystallinity lowered with a smaller meltingpeak area (Table 9). When the content of the ULTEM1000 increased, themelt viscosity increased, moldability lowered and the delaminationresistance did not improve with a large delamination width.

                                      TABLE 9                                     __________________________________________________________________________                             Melt Delamination                                      Content Tg Tc  viscosity width                                                (%) (° C.) (° C.) Tm (° C.)* (poise) (μm)           __________________________________________________________________________    Comparative                                                                         0    118 --  265 (1)                                                                             3700 50                                                Example 7                                                                     Comparative 5 120 228.8 265 (0.83) 6000 50                                    Example 8                                                                     Comparative 10  123 234.4 265 (0.67) 8200 50                                  Example 9                                                                   __________________________________________________________________________     *Parenthesized figures indicate peak area relative values                

What is claimed is:
 1. A thermoplastic resin composition which comprises(a) an aromatic polyester containing an aromatic dicarboxylic acid as amain acid component and an aliphatic glycol having 2 to 8 carbon atomsas a main diol component and (b) an amorphous polymide comprising arecurring unit represented by the following formula (1): ##STR13##wherein Ar is an aromatic group having 6 to 15 carbon atoms and R is atleast one substituent selected from the group consisting of (1) analiphatic group having 6 to 30 carbon atoms and (2) an alicyclic grouphaving 4 to 30 carbon atoms or R is (3) a combination of greater than 50mol % of at least one of said aliphatic group or said alicyclic groupand less than 50 mole % of an aliphatic group having 5 or less carbonatoms, said mole % being based on the total of R in the formula (1).andwhich contains 5 to 99.95 wt % of the aromatic polyester (a) and 0.05 to95 wt % of the amorphous polyimide (b), based on the total weight of thearomatic polyester (a) and the amorphous polyimide (b).
 2. The resincomposition of claim 1, wherein the aromatic dicarboxylic acid as a mainacid component of the aromatic polyester (a) is at least one memberselected from the group consisting of terephthalic acid and2,6-naphthalenedicarboxylic acid.
 3. The resin composition of claim 1,wherein the aliphatic glycol having 2 to 8 carbon atoms as a main diolcomponent of the aromatic polyester (a) is a glycol represented by thefollowing formula (2): ##STR14## wherein n is a number of 2 to
 8. 4. Theresin composition of claim 1, wherein the aromatic polyester (a) ispolyethylene-2,6-naphthalene dicarboxylate.
 5. The resin composition ofclaim 1, wherein in the above formula (1) representing the recurringunit of the amorphous polyimide, (b) Ar is an aromatic group selectedfrom the group consisting of ##STR15##
 6. The resin composition of claim1, wherein in the above formula (1) representing the recurring unit ofthe amorphous polyimide, (b) R is an aliphatic group having 6 to 12carbon atoms or an alicyclic group having 6 to 12 carbon atoms.
 7. Theresin composition of claim 1, wherein in the above formula (1)representing the recurring unit of the amorphous polyimide, (b) R is atleast one member selected from the group consisting of .parenopen-st.CH₂ .paren close-st._(m) (wherein m is 6 to 12,2,2,4-trimethylhexamethylene, 2,4,4-trimethylhexamethylene and CH₃ 8.The resin composition of claim 1, wherein the recurring unit representedby the above formula (1) is at least one selected from the groupconsisting of: wherein one of R' and R" is a hydrogen atom and the otheris a methyl group.
 9. The resin composition of claim 1, wherein theamorphous polyimide (b) consists essentially of recurring unitsrepresented by the following formula: ##STR16## wherein one of R' and R"is a hydrogen atom and the other is a methyl group, and recurring unitsrepresented by the following formula: ##STR17##10.
 10. The resincomposition of claim 1, which exhibits one peak derived from the glasstransition temperature when measured by a differential scanningcalorimeter (DSC) at a temperature elevation rate of 20° C./min.
 11. Theresin composition of claim 1, which comprises the aromatic polyester (a)in an amount of 40 to 95 wt % and the amorphous polyimide (b) in anamount of 5 to 60 wt %, based on the total amount of the aromaticpolyester (a) and the amorphous polyimide (b).
 12. The resin compositionof claim 1, which comprises the aromatic polyester (a) in an amount of50 to 90 wt % and the amorphous polymide (b) in an amount of 10 to 50 wt%, based on the total amount of the aromatic polyester (a) and theamorphous polyimide (b).
 13. The resin composition of claim 1, whereinthe aromatic polyester (a) comprises 2, 6-naphthalenedicarboxylic acidas a main acid component and ethylene glycol as a main diol componentand is present in an amount of 80 to 99.95 wt %, and the amorphouspolyimide (b) is present in an amount of 0.05 to 20 wt %, based on thetotal weight of the aromatic polyester (a) and the amorphous polyimide(b).
 14. A thermoplastic resin composition which comprises (a) anaromatic polyester containing an aromatic dicarboxylic acid as a mainacid component and an aliphatic glycol having 2 to 8 carbon atoms as amain diol component and (b) an amorphous polyirnide comprising arecurring unit represented by the following formula (1): wherein Ar isan aromatic group having 6 to 15 carbon atoms and R is a combination ofgreater than 50 mol % of a straight chain aliphatic group having 6 to 30carbon atoms and less than 50 mol % of an aliphatic group other thansaid straight chain aliphatic group said mole % being based on the totalof R in the formula (1),and which contains 5 to 99.95 wt % of thearomatic polyester (a) and 0.05 to 95 wt % of the amorphous polyimide(b), based on the total weight of the aromatic polyester (a) and theamorphous polyimide (b).
 15. A thermoplastic resin composition whichcomprises (a) an aromatic polyester containing an aromatic dicarboxylicacid as a main acid component and an aliphatic glycol having 2 to 8carbon atoms as a main diol component and (b) an amorphous polyimidecomprising a recurring unit represented by the following formula (1):##STR18## wherein Ar is an aromatic group having 6 to 15 carbon atomsand R is a combination of a straight chain aliphatic group having 6 to30 carbon atoms and an alicyclic group having 4 to 30 carbon atoms,andwhich contains 5 to 99.95 wt % of the aromatic polyester (a) and 0.05 to95 wt % of the amorphous polyimide (b), based on the total weight of thearomatic polyester (a) and the amorphous polymide (b).